BLOOD. 43 



blood, promote the absorption of carbonic acid from the tissues into the 

 blood, and hold other substances in solution ; the most important are the 

 sodium and potassium chlorides, the calcium and magnesium phosphates. 



Excrementitious matters are represented by carbonic acid, urea, creatin, 

 creatinin, urates, oxalates, etc.; they are absorbed from the tissues by the 

 blood and conveyed to the excretory organs, lungs, kidneys, etc. 



Gases. Oxygen, nitrogen, and carbonic acid exist in varying proportions. 



BLOOD CORPUSCLES. 



The corpuscular elements of the blood occur under two distinct forms, 

 which, from their color, are known as the red and white c^puscles. 



The Red Corpuscles, as they float in a thin layer of the Liquor Sanguinis, 

 are of a pale straw color; it is only when aggregated in masses that they 

 assume the bright red color. In form they are circular and biconcave ; 

 they have an average diameter of the ^Vtf ^ an i ncn - 



In mammals, birds, reptiles, amphibia and fish the corpuscles vary in 

 size and number, gradually becoming larger and less numerous as the scale 

 of animal life is descended, e. g. : 



TABLE SHOWING COMPARATIVE DIAMETER OF RED 

 CORPUSCLES. 



Mammals. Birds. Reptiles. Amphibia. Fish. 



Man, y fa. Eagle, T1 fo Turtle, T ^, r . Frog, T ^ B . Perch, &. 



Chimpanzee, ^jVi- Owl, 



Ourang, 7353- Sparrow, i, 



Dog, W?u- Swallow, 7 



Cat, ntW- Pigeon, 1 



H g 1^30- Turkey, , 



Horse, jeW Goose, , 



Ox, laVr- Swan, -j 



Tortoise,^,. Toad, T0 ' 53 . Carp, 



Lizard, rK V*. Proteus, fo. Pike, 



Viper, T5 Vj. Siren, ,^. Eel, 



Amphiuma, 3 3 . 



In man and the mammals the red corpuscles present neither a nucleus 

 nor a cell wall, and are universally of a small size. They can be readily 

 distinguished from the corpuscles of birds, reptiles and fish, in which they 

 \ are larger, oval in shape and possess a well-defined nucleus. 



The red corpuscles are exceedingly numerous, amounting to about 

 5,000,000 in a cubic millimetre of blood. In structure they consist of a 

 firm, elastic, colorless framework, the stroma, in the meshes of which is 

 entangled the coloring matter, the hemoglobin. 



CHEMICAL COMPOSITION OF RED CORPUSCLES. 



Water 688.00 



Globulin 282.22 



Haemoglobin 16.75 



Fatty matter 2.31 



Extractives 2.60 



Mineral salts 8.12 



